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Dec. 11, 1923. 1,477,303 c. T. ALLCUTT PROTECTIVE DEVICE WITNESSES:

ATTORNEY I INVENTOR V Fad/0 W OzwferTAl/cu/I CHESTER T. ALLCUTT, OF 'WILKINSBURG,

HOUSE ELECTRIC ANDJMANUFA CTUR-ING COMBANY,

sYLvANIiL PENNSYLVANIA, AS'SIGNORV TO wins'rni'e- A CORPORATION or PENN- rnornc'rrvn PEVIi E To all whom it may concern:

Be itknown that'I, CHss'rnn T. Annou'rr, a citizen'of the United States, and a'reside'nt of Wilkinsburg, iii-the 'rounty of Allegheny and State of Pennsylvania; have invented a new and useful Improvement in'Protecti've Devices, of which thefollowin'gis' a. specification. My invention relates to di'scharge lips as used, for-example; in hghtnl'ng arr'esters,

and it has for its object to prpvideu pargms of the character design tedthat ishall operate selectively in 'perinitting entran -passage ther'ethrough"; preferably haviiilg" iti l'ow ii'npulse ratio or, in'other w'ords," pennitciii the passage of high-frequency;*currents"at equal orlower voltages thanj currents"of normal'frequncy. In the accompanying drawing,- F igs l -'-to '8 inclusive, are-side 'views,*;pa.r tia;llj'fidiagramme ti c, illustrating various -forni of 'my" invention ,'andFi'gs. 9Land 10' are "diali grams illustrating the-much gr'eaterflegree of protection afforded bya dischargagajp having a low impulse ratio' tlia ni by one having a l'iigh -impulse ratio. 1? 1 The use of (lischarge'gaps in' connection [with transmission li-nes'is wellknowm 'said gaps being connected between line" and ground and *betweerii-line; and line, either directly or in series relation with other pr'otective apparatus such, forexamplmflas electrolytic arresterS Q; I

The function of discharge gaps of the character specified is to permit the passage of currents. of abnormal voltage suchfor example, asswilching surges and lightning disturbances; at the same time'iireventing the passage of currents of normal voltage.

Disturbances of abnormally high frequency are particularly destructive in their action because of their tendency to cause a very high eleetroinotive force between ad jacent turns of electrical windings; andgjas it is' desirable to discharge said abnormal- -fr'e quency elec'tromotive forces, even before "they have attained line 'volta I propose to construct a device which s all beiselectire with respect'to'frequ ency, discharging at equal or lower voltages at high fre u'ency than at low frequency. To this end, provide. an auxiliary electrode-or antenna in a main discharge gap and I connect said antenna to the respective members of the gap through impedance devices of dissimilar actor 16 to the-impedance character, the "relative impedances 'o'f said connectionsfa't' normal frequency, being profportibn'al" Fto-F the distance 6f the antenna fro'ni the respective'fgap terminals, whereby said antenna isa'tthe"potentialof that. por- -tion' of the electrostaticfield produced b the; mm: electrodes'yin 'Whill it lies -an -thezefo'm; ;does? notjdistilrb tl ie electrostatic 'cbriditions within the main gapi "'Ujionfthe occurrence pf a; disturbance-of other than '-li ne" frequncy, the two {con ections ofsaid antenna do'notehange propor- -tiong1tely '-'i'n iiiipetiainceg and' potential other when what ofi'the 'aumce t drtien of -tu fieId' bftl mai'melectroues isii mpresse i' upon said antenna, disturbin" the 'ial'ectrostatic conditions iutlie gap; 181% voltage between :the antenna undone-"of the gap'members is rendered-'s'o-great asto break-'- down saidfipor- 2 tion" of the main g ap';' whereuponi-tlie entire Volta e of tli r'flin'e him on the-remain' ero'f; the p, thisfe' ectglto therwith ibr izationl resu ting in the'i'ihrnej iatebreak *down b ffthe entiref suitabl" proportioni "parts of the evlce, it'is' possi le=to" oonst ruct a gap which will withstand 100,000'= volt's at 60 fcy'oles' but whiclitwill ibreak at -60,00 0 vo 1ts; .:-with Ea; single high-fie uemy "impuIsfe' -in'the' liuel" 1 I 1:"Referring-'tmFigi 1of the -drawingfor a f more detailed *understanding oi; my inventi0n,'I show a line wire at 11, said wire being connected ft'o a.= horn-shaped dischargev member'12l- An opposin g horn member 13 is connected to groundat 14, either directly or througlicurrent-limiting deyices, as desired. A small antenna 15 is mounted between the bases of the horns 12 and 13, said antenna. being connected to the born 12 through -acondensive reactor '16 and to the horn 13 through a condensive reactor-17 and an in:

ductive reactor 18. The desi is such that the ratio ofthe'irnrpedance (i ifbp in the reactors 17 and- 18, at normal line-frequency, is proportional to the distance between the members 12 and 15 and the members 15 and 13 1 respectively, "whereby the antenna I 15 does not disturb" electrostatic oonditionsuos within the gap at the frequency mentioned. Furthermore, theeondensive reactors 16 and 17 are of such value that the current passing therethroug-h at normal frequency is negligible.-

in; a gs drop in, the resystemof If it be assumed. that a high-frequency charge flows through the line wire 11, the impedance drop in the condensive reactor 16 is greatly decreased, whereas that in the inductive reactor 18 is largely increased, causing the antenna 15 to approach the horn 12 in potential and imposing a large portion of the high-frequency electromotive 'force upon the gap 13-15, whereupon said small gap breaks down, immediate y followed by the break-down of the entire gap.

In the system of Fig. 2, the general arrangement is as in Fi 1- except that the antenna 15 is connecte through a condensive reactQl 16- and a resistance member to the horn 13 is established through smalier condensive reactant-e, as indicated at 20. Adjustment is so Vma'de that the antenna 15 is at the potential of the surrounding medium at normal freqnencyand so that, with increased: frequency, the impedance drop between the members 13' and 15 ;is decreased much more in proportion than is the impedance drop between-the members 15 and 12, whereby the gap iaiagain, brok n flwn. The systenrof Fig. 2 -is tofibe preferred to hat oi Fig. l for m ny p rposesasv it i more 'convenienbto' install a resistance rod having suitable 1 impedance than to install an eqnivalentin ueti-ve reactor.

Th syst m of? ig- 13 issimilar that-of g- 2 M ind a e the PBsih 1ity ro iemploying condensive' reactors lfiand ;17"Y 0f equal sizein the connections to the horns and unb lensing. the cireuithbyi m Iohrnic resistorlthv i In the systemfof Fig. 4, eonneeti -j madefromthe here through: ai'eonden'sire v reactor 16 to a terminal'of an" inductive re actor 21, and a connection. is madeifrom the horn member 13- -tI KQughi-aeendeneive reactor] L7 to an intermediate point in said ijni ducti e eacto 21, t eenteana 15 b ing. cannected to: the remainingterminalof the-inductive reactor 21. I The operation-of the system thus indicated'issimilar'to that "of Fig. 1 except that, upon; the occurrence or a highs-frequency impulse, -the auto-transformer action ofthe reactor 2Lstill; further increases the field disturbing action of the antennato ensure an efiective break-down ofthe ap. v7

. In t e case of an .extremelytlong gap, such as is employed in highrvol tage transmission systems-, ib'ma'ybe desirable to employ two or more antennae disposed at dif disposed inthe-ga between the horn members'ii2 and 13. onnection is made from the horn member 112 to the base at the. antenna-15 through a condensi-we reactor 16 and an ohmic resistor 19;,v Connection is made between the bases of the respeotiw'ie to the member 12 19, whereas the connection antennae through a condens-ive reactor 22 and an ohmic resistor 23. Connection is also made between the baseof the antenna 24 and the horn member 13 through a condensive reactor 17. Under normal conditions, the impedance drops in the various .ortions of the charging circuit are such that the antennae 15 and 24 remain at the res ectiye potentials of the surrounding media.

he resistor 19 is preferably larger than the (5 resistor 23, in consequence of which a highfrequency surge produces a greater impedance drop between the horn member 12 and the antenna 15 than between the two antennaa, and the initial breakdown occurs at the gap 15-12. The consequent flow of cur rent through the devices 22 and 23 immediately so increases the impedance drop between the two antennae as to produce a breakdown therebetween, whereupon the entire gap breaks down.

The high frequency impulse dischar e oltage oi agap of this nature isnot radically change by a change in the shapeof the main electrodes, whereas the discharge voltage with reference to low-frequency electromotive forces may be rofoundl modified by a. change in the shape of t electrodes, i

Thus, a sphere gap, as is well known has a m hig reakdown voltag w h resp t ectromot v fome f l f or omm cial .fre ueney. than a gapof the 53min, i ing electrodes of V Byconstructing" a discharge gap inaccord-f ence with rny inyention',therefore', wherein V the the ma n eleetmd$"ha7e"ilarge t, adii-o curvatune as by being sphefficalan. fl i tour, wh as d sc a egijanten isr ricbed Lil-area, a gr t d crease-in the impulse ion ratbta n w h re lta e eefiw t ve protectiengi I I will shown in Fig. 6 agapofithis chap as e pher mm e 2 mins ranged to act-asthc seatof the mai disno charge, said discharge being bronghtabout i by an antenna.arranged;E for example, =as n Fig, 2,. although an of the other arrangements shown or st'- 1 other equivalent arrangements be employed for the energi- 116 zation of the antenna. The field distribution b tween the Spheres 25 an 2 i uc that amore radical disturbance maybe produced the-rein by the antenna 15; with a given voltage impressed upon said-antenna. no

In the form of my device shown in Fig, 7.

the arrangement is similar to that oi Fig, 6

buttheantenna itself terminates in a: sphere or similar enlarged member 27; whereby still fiurther modification ofv the discharging 1:6 characteristic is obtained. A noteworthy feature of the system; of Fig; 7 is that the antenna; 257, having" an extended surface, is not burned on pitted-by; discharges, whereby the discharging eharacteflietic is little n f to each -otiherzandiconnecfiedwtoie proportional; to s the- -di;fi'erenee,; between the existing. freqncnoyiand RO -1 ml irsquemi dicated; inethe iageemledioi mei i 1: "2 All chum-as mjmlfiififi wm zed one-15m soil jacedtisaid. disslia gemexnbem andimne' tions mboeying membe s .e q lselectrode. and; said-idisbhergenmembers re- 1 2.111 protective? eleqtnieeil diechapg glp ixppmtushitbe combination wiithetflon ch'argemembers mountedrin spacedrelation .supplYmirchit; of an a fi P-B eetro'de (mounted: adjacent said diechdrge'mombers afnd- ,connections'em w-impedaugemembersioizqdis similar character between suidi Lenxiliary electrode and said discharge members, i respectively said= connections having jimpedshoes; at the normal frequency, of :said :circuit, substantially proportiohaL-m the-distenoe between said auxiliarykelectrode and said dischargeniembers, respectively.

3. In protective ielectrical-disc]mine-gap apparatus, *the combination with two discharge members mounted in spaced relation to each other end iconnectedto a circuit of an auxiliary electrode mounted adj acentsniid discharge members, and means whereby,;-at

the normal firequen'cy of said circuit -said auxiliary electrode is; maintained atsubstantially the potential of the immediately adjacent electrostatic field set up by said discharge members, andw hereby, at. other frequencies in said suoynlv circuit. said auxiliary electrode is socharged as to disturb said electrostatic field. q

4-. In electrical spark-discliarge-gap ap paratus. thecombination with tavopdischarge membersmounte'd in spaced-relation to each other and connected to a circuit, of an euxil' iary electrode mounted adjacent said dis an smiliary electrode mounted adjacent gsaid discherge members, sndconnections embodgyimz capacitatire ,rea'c tors Qhetween saidiiauxiliary electrode and said discharge =members, riipectively V r Sir-.6 m le t i e ne i ch s ew a1 ;neretns, theeonsbination with two discharge znembers mounted, ins acedreIatiQn to each -Qthgr andeonnected to ecirei1it-,rof-,an auxto each other snd o rmnected to s, circu'iz; of 'q' .iliaryi electrode mounted adjacent; said disehergeim'embers, and. connections emb ing capaeitetiye reactors betnmen" said aux- ,iliaryelectrode .aznd sai d discharge members, pespeoti-rely the net capacitamce of; one of said, connections} exceeding that of the" oth r :7- In :protecti-ve electtifil-dischargwgap appenetus, i the combination with tw'o disichaige metmbers mounted injspaced; relation to-each-iather-and. connectedto ejcircuit, of mm euxilisry electrode mounted adjacent said flincharge -members,- and connections embodying impedance devices of such character -1Hetweensaid:euxiliary electrode and-said ,dischaxgedmembersthah upon-n change in thefrequency applied thereto.-the n'et im- 11eddnces.of-said connections cha'nge at dif- 2 -8.,S-In electrical snark-discharge-gap; ap-

Fparatus, the combination withtwo discharge 'memhersmounted in spaced relation to each oth3rand0onnected to acircuit, of an auxiliary electrodeJmmnted. adjsurent said discharge members. and connectionscnrbodying impedance devices of such character between said auxiliary electrode "and said discha ge Jncmbersthat; upon a change in the fre .ql'iencyapplied thereto, t-he'net impeglances of said connections change at different rates. ithezi-mpedances of the respective connections, .at-the normal frequency of said. circuit,rheing substantially proportional to the breakdownvoltagesof the gaps provided between said: auxiliary electrode and: the corresponding.'dis char'ge:imembers.:z w 1 -9. In protective electri -l-discharge-gap apparatus, the combination with two discharge members e mounted .in spaced relation "to each other and connected to a circuit,- of i: n'auXiliary-electrode mounted adjacent said discharge members, a. connection embodying e resistor-end e condensive reactor be- "tween'said auxiliary electrode and once]? saiddischarge' members, and a-conncction embodying. e 'cond'ensive, reactor between said auxiliary electrode and the remaining discharge member.

10. In electrical spark-discharge-gap apparatus, the combination with two discharge members mounted in spaced relation to each other and connected to a circuit, of an auxiliary electrodemounted adjacent said discharge membersaa connection embodying a resistor and a condensive reactor between said auxiliary electrode and one of said discharge members, and a connection embodying a condensive reactor between said auxiliary electrode and the remainingdischarge member, the impedances of the respective connections, at the normal frequency of said circuit, beingsubstantially proportional to the breakdown voltages of the gaps provided between said auxiliary electrode and the corresponding discharge members.

11. In an electricaldischarge" device, means providing adischarge gap, an auxiliary electrode disposed to assist in the breakdown of said gap, and means embodyin a condensive reactor connected between said auxiliary electrode andanother portion of said discharge device, said condensive re actor being formed, in art, by an'insulator servin to insulate said device. 1

12; .n an electrical-discharge device,

means rovidin "adis'char e a an aux iliary electrode disposed to assist' in the breakdownfof said gap, and means embodyin said auxiliary electrode and another portion of said discharge device, said c'o'n'densive re actor being formed, in part by a pillar-type in lato 13. In an] electr combination with a c'or'id'uctil igfriiirlber, of-

two insulators mounted adj'aceiit" thereto,

two discharge members mounted upo'n'said insulators, respectively, and jointly forming a discharge gap;- an auxiliary electrode mounted adjacent 'said apandwonnecwd 'to (meet said discharge-members*tlirougli the condensiveyreactanceof one of S aJdIIIr sulators, to ether with its immediately asso-' ciated cond ilcting member's.

14. In an electrical-discharge"device, the combinatioii wi'th a conducting member, of two insulators" mounted thereupon, discharge members" mounted upon said 'insulators arid join'tly forming a discharge gap','an auxiliary electrode mounted. proximity to said gap, and connections from said auxiliary electrode to each of said discharge members through-the condensive rcactance' provided by each of said insulators and its immediately associated conducting members, respectively.

15. In an electrical-discharge device, the combination witha conducting support, of two insulators mounted thereupon and each 7, made "up of insulating-and conducting members forming condenslve reactors, "non-con'- paratus, the combinationfwith'twodi a condensive reactor connected between icaldischarge asset,- the termediate conducting member in one of said insulators. y

16; A lightning arrester comprising two discharge gap dis osed in series relation, shunt paths embodying'dissimilar impedance'devices connected across said gaps, respectively, said impedance "devices being such that, at the normal frequency at which said arrester isto be operated, the impedance'drops therein are substantiallypropor-* tional to the break-down volta es "of the associated gaps,'respectively, an at appreciably different frequency, depart fromsaid proportionality 17. In electrical spark-discharge-ga ap scgarge H members mounted in spaced'relation to each 1 otherandwonnected wasupply circuit, 'of 0 means dependent-jun the fi'e'quency off the i supply circuit for' modifying P the 3 electro-- I static field between said discharge members;

18; protective electricahdischarge ap' apparatus; 'thef combiiiatidn with two is ch rge members'mountegl imspaeed relation to eachether'andrdnnected to' a supply cir cuit of means dependent on thiefrequencytributi'on' of the electrostatlwfiel thetwodischargemembers;

19. In" electrical" spark-discharge-ga apparatus, the'combination'with two (1150 arge Y of tli'eisupply; circuit for regulatinlf th disbetween members mountedyin spaced relation to each other; and connected to 1 a supply ci-rcuitof means for modifying the electrostatic eld between saiddischargemembe'rs, said means bein dependent om the 'frequen of-the sup y cl-rcuit for' varying the egree of mo ilficationfl '1'? i QTY-1i; r 13-32%",- ,j,

20. In protective electrical-discharge ap apparatus, the combination with two disch arge members'mounted' in spaced relation to each other and com'iected to aasource of electromotive'- force, ofnmeansamodifying the electrostatic field adj acent said discharge members so as to cause a .less' nearly uniform potential gradient to exist therein at high frequencies than at lower frequencies.

21. In electrical"spark-discharge gap ap- 1 the path of disc arge betweensa'id discharge 1 0 see, c oi seed;

: e: seer/s e e: electro tat c e adie en Said discharge members so as 3010 31156; n nearly uniform potential gradient to exist therein at frequeiie$- seen elee i ttea r s W P st me mmpesrert e deca s- M toga mply the other beingconmete :"tO a whi hwit is desired th t-cheaischarge e po ib eekr wn I of the E B5 and-means dwendent on varying the breakdown potentieLof, saidg pe gbm ng haying one side e n.

ischer e gaprcomr 9 mm Wmshss h ge ele tr d s.

m-spaeedgnelatmn to .each' other, ongoih ckiisie ng e mdi t the ungmu id d si ot'sgid --electt0 ytie=arm$ r and th o e sih ch. i conn cted-to ajs rceisupply, fieehs fer.- minethchreekdWn- W tiail tower-y with; theuqfrequeney-oacid.

pply circ it;

In: a-liglitaming-d schairgce q apparatuspmxided withtwo: spaced isehange members. means for illipnessing all-electromntive toms of: pliedfltermined, character thereacmss, the-method of ind g c d charge between' said discharge-- members comprising m'od iitying gthe potential gradient thenebetween.

26. Thecombination with an electrical spark-dischargmgwp device comprising two spaceddischairgegnembors one-of which is connected to a. source of electro-motiue force and the otherof which is connected to a circuit-to which it is desiredthat the source at electro-motive force be connected when the. discharge gap breaks down, ofi'an auxil- V inry electrode mounted adjacent to saiddischarge members: and normally electrically connected'toi both ofsaid discharge members.

27. The combination spaced discharge members one of which is connected to a, source of electromotive force and the otherof which is connected to a circuit to which it is desired that the source 1 ofelectromotive force be connected. when di po e with-an electrical spark-disohenge-gap devicecompmsmg two the discharge gap breaks down, of an auxiliary electrode mounted adjacent to. said discharge members and connected to both of said discharge members through impedance devices.

28. The-combination with means providing-"a. spark gap, of means for impressing an elcctroemotive' force of predetermine character thereacross, a. conducting member disposed in proximity to said gap and -'9'- jo n meansfo equ y i ing between the spark-gaps the normal Working voltage ofthe system to be protected- 30. Discharge gap appgiratus having an impulse ratio of'less than unity.

31. A spark gap; device baring I a lower dischar voltage at high frequencies than at r(. 1ei'.iwfi3 lower frequencies.

32. In combination with a source of clec tromotive force, :a proteetire device pror vided with a. discharge gap endmecns for causing the breakdown voltage of said gap, to vary inversely n itli'thc. frequency of the source.

33QA protective device provided Avitlnn discharge. gap comprising twospaced-electrodes, means for causing the breakdown voltage therebetwccn to decrease with an increase in the rate of change of potential of one of the electrodes.

34, In a protective device the combination with :m' electrical-discharge gap device comprising two spaced discharge members one of which is connected to a source of electromotive force and the other of which is connected to a circuit to which it is desired that said source be connected when the discharge ga-p breaks down. of an auxiliary electrode mounted adjacent to seid discharge membeis and normally electrically connectedto both of said discharge members, and means for changing the impedance between said auxiliary electrode and one of the discharge members under predetermined condL tions.

35. The combination with an electricalspa-rk-disebarge gap device comprising two spaced discharge members one oi which is connected to a source ofelectromotive force and the other ofwhich is connected to a circuit to which it is desired that said source be connected when the discharge gap breaks down, of an auxiliary electrode mounted ads Hill jacent to said discharge members and normally electrically connected to both of said discharge members, and means for changing the impedance between said auxiliary electrode and one of the discharge members upon a change of frequency of said source.

36. The combination with an electricalspark-discharge-gap device comprising two spaced discharge members one of which is connected to a source of electromotive force and the other of which is connected to a circuit to which it is desired that the source of supply be connected when the discharge gap breaks down, of an auxiliary electrode mounted adjacent to said discharge members and normally electrically connected to both of said discharge members, and means for changin the impedance between said auxiliary e ectrode and one of the discharge members in accordance with the rate of change of potential of said one discharge member.

37 In combination, a source of electromotive force, a plurality of spark discharge gap devices connected in series, means for causing the breakdown voltages of said gaps to be proportional to the length of said gaps under normal conditions and to difier therefrom under predetermined abnormal conditions.

38. In combination, a lightning arrester provided with a plurality of discharge gaps connected in series, means for causing each of said gaps to have substantially the same discharge voltage under normal conditions and to have relatively difi'erent discharge voltages under predetermined conditions.

39. In combination with a source of electrornotive force, a plurality of electrodes forming discharge ps connected in series, and means for causing the breakdown volt ages of said gaps to change differently under predetermined conditions of said source of supply.

40. In combination with a source of electromotive Force, a connection to ground comprising a plurality of discharge gap devices connected in series, said gaps being so disposed that the ionization of the surrounding medium produced by the breakdown of one of said gaps affects the breakdown Volt ages of the remainder thereof.

41. In combination with a source of electromotive force, a connection to ground comprising a plurality of discharge ga devices connected in series, and impe ance members-of dissimilar character connected across each of said gaps,

42. In combination with a source of elec tromotive force, a plurality of discharge gaps connected in series, and means for causing the voltages across said gaps to be proportional to the breakdown voltage of said gaps u on normal conditions and to differ there rom under predetermined abnormal conditions.

43. In combination, a source of electromotive force, a plurality of members arranged to form discharge gap devices connected in series, means for causing the volt ages impressed across said gaps to be proportional to the breakdown voltage of said gaps under normal conditions of said source of electro-motive force and to difier therefrom under predetermined abnormal conditions thereof.

44. In combination, two spaced main discharge members of the sphere gap type, and an auxiliary electrode of the needle point type disposed intermediate said main discharge members.

45. In combination, two s aced main discharge members of the sp ere gap type, and an auxiliary electrode of the needle point type disposed intermediate said main ischarge members and'connected to both of said main discharge members.

.46. In combination with a su ply circuit, two spaced main electrodes 0 the sphere gap type, one of which is connected to the suppl circuit and the other of which is connecte to ground, an auxiliar electrode of the needle point type dispose intermediate said main dischar e members, said needle point electrode being maintained at a po tential intermediate that of the two main tive force impressed across one of said gaps varies under redetermined conditions.

48. In combination, a plurality of discharge gap devices arranged in series relation, means for applying an electromotive force across said gaps, and additional means whereby the proportion of said electromotive force im ressed across one of said gaps varies with t e rate of change of the said electromotive force.

49. A lightning arrester having an impulse ratio of less than unity.

50. A protective device provided with a discharge gap having an impulse ratio of less than unity.

In testimony whereof, I have hereunto subscribed my name this 31st day of Jan, 1918. 

